Difference is about 7% between 4.56 and 4.88. So a cruise, you’ll see about a 7% difference. So 2500 becomes 2675. So compare that to the torque curve of the engine.
I’d not hesitate to do 4.88’s, personally. Especially if there is going to be any towing. Even if it’s just around town.. or especially if it’s just around town... or if you ever plan to go to a larger tire (bfg’s 34*11.5 looks like a great DD size), then I’d also go 4.88. My wife doesn’t know this, but I’m sincerely thinking of putting 4.88’s in her gen5 4Runner. 😁
For speedo, I used a Yellr box with the pigtail. Works awesome. Www.yellr.com
Unless you plan on going to 35s later I wouldn't hesitate to go 4.56s. I actually have a full 3rd member with 4.56's and a trd kazuma limited slip if you are interested. I have no need for it anymore. To get back to stock reading on 33s you need (iirc) 4.30 gears, with 4.56s you get a nice torque bump without a huge hit on mpg.